Telephone system



Connector Second Selector 9 F. H. W IEGAND TELEPHONE SYSTEM Filed April 22, 1943 First Selector 6 m 0 00000 0000 0 0 0000 0000 00000 0 000 0 0 0000 0 0000 000 000 00 00 00000 0 00 00 8 00000 0 oo o 0 0000 0 00 00 0 0000 0 00 00 000000000 0 0000 0 00 00 0 0000000 00 0 0000000 00 I 0 0000 0 00 00 7 0 0000 0.0Mw0 3 I 8 0000000 0 0 0000 00000 5 J 0 0 0 000 000 Ov v 0 0000 0 0000 0 0 0 0 000 000 l -I m 4 00 000 0000 0000000000 0020000000 0000000000. 5 I 0 0 0 0 00 0 000 1 1 5 p 0 000 000 000 M J F 1 vnocooooooo 4 0000000000 4 0 0 0000000 00 M 00 0 000 000 0000000000 4 oooconooo 00000000 00 00000000 00 z e Fahd 2 Get. 17, 1944.

Connector INVENTQR B Wziqal wd Rwu. 0S ATTORNEY Patented Oct. 17, 1944 TELEPHONE SYSTEM FrankH. Wiegand, Pasadena, Calif., assignor to American Telephone and Telegraph Company,

a corporation of New York Application-April 22, 1943; Serial No. 483,985

' j 3 Claims] ((31.179-18) This invention relates to telephone systems and more particularly to improvements in automatic telephone systems of the step-by-step t p I l V More specifically, the invention relates to improvements inthe connectors-used in such stepby-step systems whereby the regular trunk-hunt ing connector may operate as a level-hunting connector over certain levels of the connector.

, Such an arrangement would be particularly advantageous in instances where a customer applies for a P. B. X systemhaving over ten trunks, as for example, between ten and twenty trunks, in' an ofiice where there has previously been no requirement for level-hunting service and where the installation of any'other large P. B. X system in the near future is unlikely. By providing the regular rotary trunk-hunting connector with the arrangements of the invention the expense of installing a group of level-hunting connectors for such a customer would be avoided and the rotaryhunting action on the other levels not assigned to this customer is retained. With the arrangements of the invention a larger'number of small systemsmay 'beasigned in the hundred trunk group of the connector than if a group of levelhuntingf 'connect'ors were installed. Other ob-' jectsand features of the invention will'be more clear from the detailed description thereof hereinafter given.

The invention may be more fully understood from the following description together with the accompanying drawing in the Figures 1 and 2 of which the invention is illustrated. Fig. 1 shows schematically a ste pf-by-step telephone system to which the arrangements of the invention are applic'able. Fig. 2 shows in detail the circuit ar rangements of the invention. Similarreference characters have been used to denote like parts in bothfiguresh In the step-by-step telephone system illustrated schematically in Fig. l'there is shown a calling subscribers dial telephone set I, a line finder 2, a first selector 6, a second selector '9, a connector I2 and a trunk I3 leading to the called subscriber. For purposes of illustration it may be assumed that the called subscribers number is 8249. The act of taking the receiver off the hook will start a line finder, such as 2, in operation to locate and make a connection with the calling subscriber. The call will then be extended over the wiper arm 3 and trunk 4 to the wiper arm 5 of the first selector -6 and a dial tone will be sent back to the calling subscriber who will then dial the number82rl9. The dialing of number- 8 will cause the wiper arm 5 to move up t the eighth level of contacts and then the selector will move horizontally along this level until an idle trunk is found. The call'will then be extended over trunk to the ,wiper arm 8 of the second selector 9. The dialing of number 2 will cause the wiper arm 8 to move up to the second level of contacts and then the selector will move horizontally along this level until an idle trunk is found. The call will then be extended over trunk I!) to the wiper arm ll of the connector I2. The connector I2 is ofthe rotary trunk-hunting type. The dialing of number 4 will cause the wiper arm to move up to the fourth level of contacts and the dialing of the number 9 will cause it to move horizontally along this level to the ninth contact. The call will then be completed over trunk l3 to thecalled subscriber. The foregoingarrangements are well known in-the art.

' To the rotary trunk-hunting connector [2 there might be connected one hundred individual subscribers" trunks; such as i3, or there might be connected thereto a lesser number of subscribers lines and'a number of private branch exchanges. In order to accommodate a subscriber who de sired a private branch exchange with more than tentrunks, as for example, between ten and twenty-trunks, the connector might be changed from therotary trunk-hunting type to the levelhunting type.- In the level-hunting type of con nector the wiper arm would move up to a certain level of contacts and then move horizontally over this level until an idle trunk was found and if no idle trunk existed on thislevel, it would automatically move to the next level of contacts and search on that level 'until an idle trunk was found. With such an arrangement one subscriber could readily be supplied with a private branch exchange of twenty trunks but the other eight levels of contacts could only serve one subscriber apiece. Accordingly a level-hunting connector would only be economical if it were serving a number of relatively large private branch exchanges.

In the arrangements of the invention the ordinary rotary trunk-hunting connector is modified so that it will operate as a level-hunting connector over a certain of the levels of contacts but not over the other levels. Over these other levels it will function as a trunk-hunting connector. In other words, with the arrangements of the invention the connector will provide both trunk-hunting and level-hunting. The arrangements for accomplishing this are shown in Fig. 2.

If a customer desired a private branch exchange with between ten and twenty trunks, or for purposes of illustration, twenty trunks, two levels of contacts of the connector would be assigned to him. It might be desirable to assign the customer the two upper levels in this instance. It is pointed out that whenever a connection is made with any of the ten trunks connected to the top level, ground would be applied to the sleeve conductor of said trunk in a. manner well known in the art. In accordance with this invention a chain of ten relays would be provided having a relay individual to each of the said ten trunks. Three of these are shown as R1, R4 and R10. However, it

is understood that one relay would be provided for each trunk. Each relaywould be connected in a circuit completed over the sleeve of its re-'-" spective trunk. Accordingly, whenever a connection is made with a trunk, its associated relay would operate. This chain of relays has associated therewith acircuit l5'whichwould be completed over the contactsofall. of said; relayswhen they are operated. The circuit L5 would also have included therein a switch |6-, a resistance-19 which might be of 50 ohms and the winding; of the customary stepping magnet l4. The winding: of the stepping magnet 14- wouldbe connected tobattery l8. The other end of circuit I4 would be connected to battery I1.

7 As heretofore pointed out'thetwoupper levels of ninth and tenth levels'are assigned to theicustomer with the twenty trunkprivate branch. exchange. When his number, which. wouldbe that corresponding to one of. the terminals: on the tenth level, is dialed, the wiper arm Ll will move to the. tenth level if there are any idle, trunks. on this level and will then move horizontally and pick out an idle trunk. In movingto; this: tenth level it will cause the cam switch I6 to.- close when it reaches the ninth level. As heretofore pointed out circuit i5 is completed over the contacts of all of the ten R relays. in the chain and hence if there is an idle. trunk. in the tenth level the circuit IE will notbe completed. However, if all of the trunks on the. tenth level are busy, all of the R relays will be operated and hence when thewiper arm II reaches the ninth level and closes the cam switch I6, circuit 1,5, will. be completed. This will connect a 50-.ohm battery to battery shunt around the stepping magnet l4 nd cause it to cease functioning regardless. of the dialing impulses. The wiper arm Ill hence will only reach the ninth level to pick out an idletrunk therein. In other words, with the arrangements of the invention, whenever this particular private branch exchange numberis dialed thewiper arm will always. pick out an idle trunk on the. tenth level if one exists, but if all the trunks on the tenth level are busy it will be stopped atthe ninth level and will pick out, an idle trunk on that level if one exists.

While the invention has been disclosed as adapted to provide level-hunting action on two levels, it might readily be adapted to provide level-hunting action on more than two levels. By providing two or more chain relay circuits the arrangements of the invention could readily be extended to give level-hunting action on three or more levels. While the invention has been disclosed as embodied in certain specific forms which are deemed desirable, it is understood that it is capable of embodiment in many and other widely varied forms without departing from the spirit of the invention as defined by the appended claims.

What is claimed is:

1. In an automatic telephone system of the step-by-step type, a connector of the rotary trunk-hunting type having a single set of wipers, a. series of relays having a, relay individual to each trunk of a certain level olf said connector, circuits for each of said. relays whereby when its associated trunk is busy the relaY-willbeoperated, and a circuit controlled by said chain of relays and operative when all of said relays are operative for holding saidset of wipersof. said connector at the level justbelow. said firstmentioned level so that it may Search tor an. idle. trunkin said second mentioned level.

2. In an automatic. telephone system of the step-by-step type, aconnector of the rotary trunk-hunting type havinga single set of. wipers, a series of relays-having a relay individual to each of the trunks of the top level, of said; connector, circuits; for each of said relayswhereby: when its associated trunk is busy the relay. will be. oper-. ated, a switch, a circuit. completed over said switch and over the contacts of all of said series of relays. when operated for halting said set of wipers of said connector, at the level. just below said top level so that it may search for an idle trunk in said second mentionedv level, and means to close said switch when. said set, of wipers of said connector reaches the level; of saidconnector below said topleveL.

3. In an automatic telephone system of the step-by-step type, a connector. of the rotary trunk-hunting type having a single set oi wipers, a plurality of chains of relays each individual to different levels, of said connector each of said chains having a relay individual to each of the trunks of the. level with which the chain is associated, a plurality of circuits individual to each of said chains of relays, each of said circuits being adapted to be completed when all the relays, o

its associated chainare operated, and means controlled by each of' said circuits when completed for halting said set of wipers. at a level of just below the level with which a completed one of said circuits is associated.

FRANK H. 

